1. Field of the Invention
The present invention relates to uninterruptable power supply (UPS) systems. More specifically, the present invention relates to a system and operating method using a portable computer system to emulate the operations of a UPS.
2. Description of the Related Art
A server is a computer which manages common data and peripherals such as mass data storage devices, printers and modems, and supplies the common data in a network of multiple nodes connected to workstations. The common data is typically the most valuable asset in a network and the server, as manager of the data and peripherals, is charged with the responsibility for the integrity and protection of the data. A server common fulfills this responsibility through the usage of an Uninterruptable Power Supply (UPS) to maintain reliable operation and data storage through brownout and AC line dropout conditions.
A UPS is a device that is independent from other components and subsystems in the network and is connected into the network to protect common network data. FIG. 1, labeled prior art, is a block diagram illustrating a conventional UPS control system 100. The UPS control system 100 includes an Uninterruptable Power Source (UPS) 101 with a rechargeable battery 102, an AC line charger 104 connected to charge the battery 102 from the AC line source 108, and an electronic control circuit 106 for regulating charging of the battery 102 and selecting the source of operating power between the battery 102 and the AC line source 108. Various types of rechargeable batteries may be used, such as nickel-cadmium (NiCad) batteries. More advanced versions of uninterruptable power supplies, such as the illustrative UPS control system 100, include a serial cable 110 for communicating signals generated by the electronic control circuit 106 to a server 112. The serial cable 110 commonly uses a custom design cable protocol, rather than a standard cable protocol such as the RS-232 standard.
The server 112 includes a computer 113 executing software including a UPS server software 114 and applications routines 115. An administrator 117 is an application routine 115 that exercises control over the application routines 115 and the server 112. The UPS server software 114 operates in conjunction with a server operating system 116 to receive signals at a serial port 118 via the serial cable 110 that are indicative of a UPS low battery status condition of the battery 102 and an AC line status condition of the AC line source 108. The server operating system 116 includes a system Basic Input/Output System (BIOS) 120 that controls various communication tasks. Among other tasks, the BIOS 120 controls the communication between the UPS server software 114 and the serial port 118.
In response to predetermined conditions of the UPS low battery status and the AC line status, the UPS server software 112 may generate a signal directing the UPS 101 to shutdown, either a partial or total shutdown. The electronic control circuit 106 drives the nonstandard protocol of the serial cable 110, typically by forcing selected line signals to high and low states which are detected by the UPS server software 114.
The conventional UPS control system 100 operates by responding to signals generated by the UPS 101. For example, when the AC power fails, the UPS 101 asserts a predetermined signal on the serial cable 110. The signal on the serial cable 110 is transmitted to the serial port 118 and, through the operation of the BIOS 120, activates a routine executing in the UPS server software 114. The UPS server software 114 sends a message to the applications routines 115 informing the applications that the system is to be shut down. Alternatively, the UPS server
software 114 sends a message to the administrator 117 that the AC line power has failed.
When the UPS 101 detects a low battery condition, the UPS 101 asserts a predetermined signal on the serial cable 110 that is indicative of the low battery condition and requests shutdown of the server 112. The UPS server software 114 responds to the low battery condition signal by sending a notification to the applications routines 115 that shutdown in imminent and transmits a signal to the UPS 101 requesting termination of power. The applications respond to this signal by saving data and status information in a nonvolatile storage prior to system shutdown.